Delivery systems for administering a beneficial agent to a biological, fluid environment of use are known to the prior art. See, for example, U.S. Pat. No. 3,845,770; U.S. Pat. Nos. 3,916,899; 3,995,632; 4,111,202; 4,111,203; 4,203,439; 4,327,725; and 4,612,008.
The delivery devices described in the above patents operate successfully for their intended use and they can deliver many beneficial agents for their intended effects. Now, it has been observed that their use can be limited because they lack the necessary elements to deliver beneficial agents that are sensitive to fluids and to fluids containing biological gases. Their use may be limited because beneficial agents that are sensitive to such aqueous-biological fluids or to other fluids external to the delivery device may be adversely affected by fluids that enter the device and contact the beneficial agents during operation of the device. Examples of such fluid-sensitive agents include proteins, peptides, and hormones. Moreover, the prior art devices lack the necessary means for their use as implant devices for dispensing such sensitive agents to a biological fluid-rich environment of use.
It will be appreciated by those versed in the dispensing arts that if a delivery system is provided for administering at a controlled rate and for protecting a beneficial agent that is sensitive to aqueous and biological fluids, and which delivery system possesses the kinetic ability to deliver the protected beneficial agent in effective amounts over time, such a delivery system would have a positive value and represent an advancement in the dispensing arts. Likewise, it will be self-evident to those versed in the implant art that a pressing need exists for an implant that is essentially free of the tribulation associated with the prior art and that, if such an implantable delivery system is provided, it would have a practical application in the fields of human and veterinary medicine and in the breeding and management of farm animals.